Excellent freeware birthday tracker with address book integration. Just recently saw realized it and moved Geb's birthdays to the Address Book, then used an applescript from there to schedule e-mail alarms for them all via iCal.
I did find a bug, though - after moving all birthdays from GeburtstagsChecker into Address Book I noticed that the app no longer announced any birthdays that had recently passed, only those yet upcoming.
The announcement window does not stick where nudged. Yes, which corner it sits in is controlled via Preferences. But I like to tuck it all the way against the screen, not buggered by a couple pixels. I'd also like a way to have the Birthday List window show on launch. I always have to open the app, then hit command-2 to summon it.